Retractable blade knife

ABSTRACT

The retractable blade knife of the present invention is designed to have the minimum number of parts and to require the minimum amount of fabrication. The casing is in two parts, namely, a body of molded plastic and a cover of pressed sheet metal, which come apart for removal and replacement of the blade. The operating button has a flange which engages notches in inwardly drawn skirts of the cover, the skirts surrounding a slot through which the button extends. An arched cantilever spring is welded at one end to the blade carrier. The button is mounted on the arch of the spring intermediate its ends. The other end of the spring holds the blade against the base of the blade carrier, location of the blade being by upstanding lugs of the blade carrier engaging edges of the blade tang and a keyhole slot in the blade. There is no screw thread in or on the knife.

United States Patent Reaney et a1. Feb. 4 1975 1 1 RETRACTABLE BLADE KNIFE 3,453,729 7/1969 Larson 30/329 x [75] In e to A b a ey, am; Michael 3,660,895 5/1972 West 30/162 Taylor both of England Primary Examiner-A1 Lawrence Smith [73] Assignee: Stanley Tools Limited, Woodside, Assistant Examiner.l. T. Zatarga Sheffield, England Attorney, Agent, or FirmPrutzman, Hayes, Kalb & 221 Filed: May 23, 1973 The retractable blade knife of the present invention is [30] Forelgn Apphcatlon Prmmy Data designed to have the minimum number of parts and to May 26, 1972 Great Britain 25061/72 require the minimum amount of fabrication. The casing is in two parts, namely, a body of molded plastic [52] US. Cl 30/162, 30/320, 30/336, and a cover of pressed sheet metal, which come apart I 30/338, 30/339 for removal and replacement of the blade. The operat- [51] Int. Cl B26b l /08 ing button has a flange which engages notches in inl l Field Of Search 30/162. 335, 93, wardly drawn skirts of the cover, the skirts surround- 30/336, 337, 338, 339 ing 'a slot through which the button extends. An arched cantilever spring is welded at one end to the 1 References Cited blade carrier. The button is mounted on the arch of UNITED STATES PATENTS the spring intermediate its ends. The other end of the 174 417 3/1876 Evans 30/162 spring holds the blade against the base of the blade 2.0161107 10/1935 Forsberg 30/335 ux carrier, location Of the blade being y upstanding lugs 2,548,797 4/1951 Ingwer 6161, 30/162 of the blade carrier g g g edges Of the blade g 2,608,890 9/1952 Andrews 30/162 X and a keyhole slot in the blade. There is no screw 2,870,537 1/1959 Ortner 30/162 thread in or on the knife. 3,314,148 4/1967 FOClll'l'll 30/162 3,316,635 5/1967 Merrow e1. a1. 30/162 13 Claims, 4 g Flgures n 16 42 )3 41 1 2 38 14 4 26 28 5 i i a .11.! 4 I 23 1 2044 I5 30 49 PATENTED FEB 75 SHEET 1 OF 2 PATENTEUFEB 4191s SHEET 2 [IF 2 depression of button 21 for extension or retraction of the blade 11.

It is pointed out that the spring 22 carries out all three functions of firstly attaching the button 21 to carrier 13,;secondly engaging the blade 11 to hold the blade 11 in position relative to the carrier member 13 and thirdly operatingthe facility for reliable locking of the blade 11 in the different positions and is the only I spring in the knife 10.

It is also pointed out that-no part of theknife is screw-threaded. v

The body 14 is formed with a facility in the form of a hole 49 to allow for hanging the knife 10 on a hook, not shown, connection of the knife to a keyring, not shown, attachment of the knife to a string anchorage, not shown, or the like.

We claim:

l. A retractable blade knife comprising a casing having a slot in one side thereof, a blade, a slidable blade carrier mounting the blade and engaging at least one edge thereof, an operating button projecting through said side slot and a leaf spring associated with the operatingbutton for biasing thebutton into selective locking engagement with the casing and for removably holding the blade on the blade carrier, said casing comprises a body having a slot in'one end through which the blade can be extended and 'retracted'and a cover detachably attachable to the body to enclose the blade carrier and spring, wherein the cover-has two curled opposite end portions which respectively hook over two corresponding end portions of the body, firstly one end portion of the cover being hooked over one end portion of the body and then the cover being pivotable thereabout until the other end portion of the cover hooks over the other end portion of the body, whereby the cover can snap into place when attached to the body.

2. A retractable blade knife as claimed in claim 1 wherein the slot through which the operating button projects is in the cover.

3. A retractable blade knife as claimed in claim 1 wherein the body is of molded plastics material and'the cover is of sheet metal.

4. A retractable blade knife as claimed in claim 1 wherein two, sides of the body have rebates for the cover to nest therein.-

5. A retractable blade knife as claimed in claim 1 wherein the spring is'an arched cantilever spring which a is permanently attached to the blade carrier.

6. A retractable blade knife as claimed in claim 1 wherein the operating button is biased by the leaf spring into engagement with detents in the casing to lock the blade selectively not only in the extended and retracted positions but also in an intermediate position.

7. A retractable blade knife as claimed in claim 1 wherein no part of the knife is' screw-threaded.

8. A retractable blade knife as claimed in claim 1 wherein the casing is formed with a facility in the form of a hole to allow for hanging the knife on a hook,- con- 4 nection of the knife to a key ring, attachment of the knife to a string anchorage, or the like.

9. A retractable blade knife as claimed in claim 1" wherein the slot through which the operating button projects is in the cover;

wherein said cavity is large enough to provide'additional blade storage space; I

wherein the body is of molded plastics material and the cover is of sheet metal;

wherein two sides of the body have rebates .for the cover to nest therein;

wherein the spring is an arched cantilever spring which is permanently attached to the blade carrier;

wherein the operating button is biased by the leaf spring into engagement withthe detents in the casing to lock the blade selectively not only in the extended and retracted positions but also in an intermediate position;

wherein a plurality of edges of the blade are engaged by the blade carrier to locate the blade in a given 1 position relative to the blade carrier; wherein a tang ofthe blade is abuttingly engaged by a rearward pair of lugs and a forward pair of lugs, said pairs of lugs forming part of the blade carrier; the rear end'of the tang is abuttingly engaged by a forwardly directed lug ofthe blade carrier; and the rear end of a keyhole slot in, the tang is abuttingly engaged'by arearwardly directed lug of the blade carrier; the leaf spring pressing the blade against a base of the blade carriensaid lugs all upstanding from the base of the-blade carrier; wherein, for releasably locking the blade and blade carrier as a unit releasably in different positions, including at least the extended position and the retracted position, relative to the casing, the button is formed with a flange'which can seat in between any one of three pairs of detent-forming notches which are formed in two inwardly drawn skirts of the cover, the skirts extending along the sides of the slot through which the button projects; 1 wherein the button is attached to an arched portion of .the spring intermediate positions at which the' spring respectively is attached to the blade carrier and engages the blade, so that the flange can be unseated by depression of the button for extension or retraction of the blade;

wherein no part of the knife is screw-threaded; and

wherein the casing is formed with a facility in the 11. A retractable blade knife as claimed in claim 10 wherein a tang of the blade is abuttingly engaged by a rearward pair of lugs and a forward pair of lugs, said pairs of lugs forming part of the blade carrier; the rear end of the tang is abuttinglyengag'ed by a forwardly di rected lug of the blade carrier; and the rear end of a keyhole slot in the tang is abuttingly engaged by a rearwardly directed lug of the blade carrier; the leaf spring pressing the blade against a base of the blade carrier; said lugs all upstanding from the base of the blade carrier.

. l RETRACTABLE BLADE KNIFE BACKGROUND OF INVENTION SUMMARY 'OF THE INVENTION The retractable blade knife of the present invention comprises a casing, a blade, a slidable blade carrier, an operating button and a leaf spring, wherein the operating button projects through a slot in one side of the casing, wherein the operating button is connected to the blade carrier by the leaf spring, wherein the blade carrier engages at least one edge of the blade for locating theblade, wherein the operatingbutton is biased by the leaf spring into engagement with detents in the casing to lock the blade selectively in extended and retracted positions, and wherein the casing is adapted to be opened for removal and replacement of the blade. The retractable blade knife of the present invention is characterised in. that the leaf spring bears against one face of the blade to hold the blade removably tothe blade carrier. I 1

Preferably the casing comprises a body and a cover, the body having in one end a slot through which the blade can be'extended and retracted, the body also having a cavity therein for the blade when retracted and for the blade carrier, the cavity'having an opening at one side of the body for removal oftheblade carrier together with the blade, the cover being detachably attachable to the body to close the cavity opening, and

the cavity. providing an additional blade storage space.

Preferably the slot through which the operating button projects is in the cover. I

Preferably. the operating button is biased by the leaf spring into engagement with the detents in the casing to lock the blade selectively not only in the extended and retracted positions but also in'an intermediate positioll. 1

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates in side elevation a preferred retractable blade knife in accordance with the invention, showing the blade fully retracted;

FIG. 2 is a similar view at the same scale of the knife illustrated in FIG. 1 but with the blade fully extended and the cover removed and with a spare blade in the cavity;

FIG. 3 is a section on line Illlll in FIG. 2 but at twice the scale of FIGS. 1 and2; and

FIG. 4 is an exploded view of the knife at the same 7 scale as FIG. 3.

DESCRIPTION OF- THE PREFERRED EMBODIMENT 11. The cover 15 is detachably attachable to the body 14 to close the cavity opening 19. A- manually operable button 21 is connected to the blade carrier 13 by being attached to a light, arched cantilever leaf spring 22 which is itself permanently attached at 23 by being welded to the blade carrier 13 and which engages one face of the retractable blade 11 at 24 to hold the blade 11 removably to the blade carrier 13. The button 21 projects through an elongate slot 25 in the cover 15 at one side of the casing 12 for manual extension and retraction of the blade 11. The cavity 18 provides additional blade storage space for a spare blade 26 as shown place when attached to the body 14. Sides 31 and-32 of the body 14 have rebates 33 for the cover 15 to nest therein. The cover 15 can be detached from the body 14. by simply pushing the cover end portion 28 up so as to unhook the cover end portion 28 from body end portion and then unhooking cover end portion 27 from body end portion 29.

Edges of the blade 11 are engaged by the blade carrier 13 to locate the blade 11 in the given position as shown relative to the blade carrier 13. (The blade carrier 13 is also of pressed sheet metal.) More particularly: a tang 34 of the blade 11 is abuttingly engaged by a rearward pair of lugs 35 and a forward pair of lugs 36, the lugs 35 and 36 forming part of the blade carrier 13; the rear end 37 of the tang-34 is abuttingly engaged by a forwardly directed lug 38 of the blade carrier 13; and

the rear end 39 of a keyhole slot 40 in the tang 34 is abuttingly engaged by a rearwardly directed lug 41 of the blade carrier 13. The leaf spring 22 presses the blade 11 against a base 42 of the carrier 13. The blade 11 can be detached from the carrier 13 (and reattached thereto or replaced by the spare blade 26) when the blade carrier 13 has been removed, together with the blade 11, from the cavity 18. The arrangement of the lugs 38 and 41' so that each is directed towards the other provides positive, bi-directional blade location. The lugs 35, 36,38 and 41 are all upstanding from the base 42. Of course, the necessary clearance is provided between the blade 1 1 and the lugs 35, 36, 38 and 41 for easy removal and replacement of the blade 11.

The free end of the spring 22 is lightly loaded towards the base 42. The dimensions, geometry and properties of the spring 22 are sov selected as to allow the blade tang 34 to be easily pushed between the base 42 and the spring 22, until the blade 11 becomes located-and lightly retained by the lugs 35, 36, 38 and 41.

When putting the blade 11 and carrier 13, already assembled together, into the casing 12, the sharp end 1 1a of the blade 11 is fed through the cavity opening 19 into the cavity 18 and then through the slot 17, whereafter the carrier member 13 is allowed to fall into the cavity 18.

For releasably locking the blade 11 and blade carrier 13 as a unit in different positions, including a fully extended position, a fully retracted position and an intermediate position, relative to the casing 12, the button 21 is formed with a a flange 43 which can seat in between any one of three'pairs of notches 44, 45 and 46 LII the blade.

projects.

13. A retractable blade knife as claimed in claim 12 wherein the button is attached to an arched portion of the spring intermediate positions at which the spring respectively is attached to the blade carrier and engages the blade, so that the flange can be unseated by depression of the button for extension or retraction of 

1. A retractable blade knife comprising a casing having a slot in one side thereof, a blade, a slidable blade carrier mounting the blade and engaging at least one edge thereof, an operating button projecting through said side slot and a leaf spring associated with the operating button for biasing the button into selective locking engagement with the casing and for removably holding the blade on the blade carrier, said casing comprises a body having a slot in one end through which the blade can be extended and retracted and a cover detachably attachable to the body to enclose the blade carrier and spring, wherein the cover has two curled opposite end portions which respectively hook over two corresponding end portions of the body, firstly one end portion of the cover being hooked over one end portion of the body and then the cover being pivotable thereabout until the other end portion of the cover hooks over the other end portion of the body, whereby the cover can snap into place when attached to the body.
 2. A retractable blade knife as claimed in claim 1 wherein the slot through which the operating button projects is in the cover.
 3. A retractable blade knife as claimed in claim 1 wherein the body is of molded plastics material and the cover is of sheet metal.
 4. A retractable blade knife as claimed in claim 1 wherein two sides of the body have rebates for the cover to nest therein.
 5. A retractable blade knife as claimed in claim 1 wherein the spring is an arched cantilever spring which is permanently attached to the blade carrier.
 6. A retractable blade knife as claimed in claim 1 wherein the operating button is biased by the leaf spring into engagement with detents in the casing to lock the blade selectively not only in the extended and retracted positions but also in an intermediate position.
 7. A retractable blade knife as claimed in claim 1 wherein no part of the knife is screw-threaded.
 8. A retractable blade knife as claimed in claim 1 wherein the casing is formed with a facility in the form of a hole to allow for hanging the knife on a hook, connection of the knife to a key ring, attachment of the knife to a string anchorage, or the like.
 9. A retractable blade knife as claimed in claim 1 wherein the slot through which the operating button projects is in the cover; wherein said cavity is large enough to provide additional blade storage space; wherein the body is of molded plastics material and the cover is of sheet metal; wherein two sides of the body have rebates for the cover to nest therein; wherein the spring is an archEd cantilever spring which is permanently attached to the blade carrier; wherein the operating button is biased by the leaf spring into engagement with the detents in the casing to lock the blade selectively not only in the extended and retracted positions but also in an intermediate position; wherein a plurality of edges of the blade are engaged by the blade carrier to locate the blade in a given position relative to the blade carrier; wherein a tang of the blade is abuttingly engaged by a rearward pair of lugs and a forward pair of lugs, said pairs of lugs forming part of the blade carrier; the rear end of the tang is abuttingly engaged by a forwardly directed lug of the blade carrier; and the rear end of a keyhole slot in the tang is abuttingly engaged by a rearwardly directed lug of the blade carrier; the leaf spring pressing the blade against a base of the blade carrier; said lugs all upstanding from the base of the blade carrier; wherein, for releasably locking the blade and blade carrier as a unit releasably in different positions, including at least the extended position and the retracted position, relative to the casing, the button is formed with a flange which can seat in between any one of three pairs of detent-forming notches which are formed in two inwardly drawn skirts of the cover, the skirts extending along the sides of the slot through which the button projects; wherein the button is attached to an arched portion of the spring intermediate positions at which the spring respectively is attached to the blade carrier and engages the blade, so that the flange can be unseated by depression of the button for extension or retraction of the blade; wherein no part of the knife is screw-threaded; and wherein the casing is formed with a facility in the form of a hole to allow for hanging the knife on a hook, connection of the knife to a key ring, attachment of the knife to a string anchorage, or the like.
 10. A retractable blade knife as claimed in claim 1 wherein a plurality of edges of the blade are engaged by the blade carrier to locate the blade in a given position relative to the blade carrier.
 11. A retractable blade knife as claimed in claim 10 wherein a tang of the blade is abuttingly engaged by a rearward pair of lugs and a forward pair of lugs, said pairs of lugs forming part of the blade carrier; the rear end of the tang is abuttingly engaged by a forwardly directed lug of the blade carrier; and the rear end of a keyhole slot in the tang is abuttingly engaged by a rearwardly directed lug of the blade carrier; the leaf spring pressing the blade against a base of the blade carrier; said lugs all upstanding from the base of the blade carrier.
 12. A retractable blade knife as claimed in claim 1 wherein, for releasably locking the blade and blade carrier as a unit releasably in different positions, including at least the extended position and the retracted position, relative to the casing, the button is formed with a flange which can seat in between any one of three pairs of detent-forming notches which are formed in two inwardly drawn skirts of the cover, the skirts extending along the sides of the slot through which the button projects.
 13. A retractable blade knife as claimed in claim 12 wherein the button is attached to an arched portion of the spring intermediate positions at which the spring respectively is attached to the blade carrier and engages the blade, so that the flange can be unseated by depression of the button for extension or retraction of the blade. 